About 4 percent of Catholic priests have been accused of sexually abusing minors over the past half-century, according to a draft of the first comprehensive study of sexual abuse within the Catholic Church in the United States. The percentage is higher than many people, including church officials, had anticipated.

The draft of the study, done by John Jay College of Criminal Justice for the US Conference of Catholic Bishops, found that 4,450 of the 110,000 priests who served between 1950 and 2002 were accused of sexual abuse of minors, according to CNN, which reported yesterday that it had reviewed the draft.

The number of alleged perpetrators given in the draft study is higher than the tallies by news media outlets, including the Associated Press and The New York Times, that have tried to count reported allegations nationwide.

The number is also higher than that projected by church officials. A top Vatican official, Cardinal Joseph Ratzinger, said in 2002, according to the Catholic News Service: "In the United States, there is constant news on this topic, but less than 1 percent of priests are guilty of acts of this type."

But the number of victims is lower than expected by many.

In December, Santa Clara University psychology professor Thomas G. Plante, estimating that about 2 percent of clergy had abused a minor, predicted that the John Jay study would indicate 24,000 victims of abuse by 3,000 priests. In 1993, the Rev. Andrew M. Greeley, a sociologist at the University of Chicago, estimated that between 2,000 and 4,000 priests had abused minors, and predicted more than 100,000 victims; last year, Greeley wrote that he suspected 4 percent of priests had abused minors. Plante and Greeley's projections were published in America magazine, a Jesuit weekly.

The study of the nature and scope of abuse by Catholic priests is scheduled to be released, along with another study of the causes of the abuse, on Feb. 27 by the National Review Board, a panel of laypeople appointed to study the abuse crisis by Bishop Wilton D. Gregory, president of the US Conference of Catholic Bishops. Officials of the bishops conference and the National Review Board yesterday did not dispute the numbers reported by CNN, but declined to confirm them and cautioned that the reports are not complete. Officials of John Jay College in New York, which is conducting the quantitative study by surveying every diocese in the United States, could not be reached for comment.

"Both the John Jay report and the National Review Board report are still in the process of being written, and people should not draw any conclusions until Feb. 27, by which date the reports will be completed and released," said Washington attorney Robert S. Bennett, a review board member who is overseeing the board's study of the causes of the sexual abuse.

Another review board member, William R. Burleigh, said he was disappointed by the leak because the board thinks it is important to put the numbers in context with the report about causes.

"The Review Board does not have the John Jay report, and we have been told it's not finished -- it's still in fragments," said Burleigh, former chief executive of E. W. Scripps Co. "But obviously we're disappointed. We wanted to release the board report and the John Jay numbers together, so we could put the numbers in context. And I have no way of knowing whether these numbers are accurate."

Gregory issued a statement yesterday saying that he has not seen the reports and cannot comment on their substance, but that the bishops conference "is prepared to respond to the reports when they are finalized and released on Feb. 27 by the National Review Board."

Gregory also reiterated the bishops' commitment to reach out to victims of abuse and to try to prevent future abuse.

Victims groups reacted to the numbers with skepticism, saying that they believe not all of the victims have come forward and that they do not trust bishops to report allegations fully.

"While we're convinced this is underreported, it still is a tragic story of thousands of people suffering very private pain, and a tremendous amount of that pain could have been prevented," said David Clohessy, national director of the Survivors Network of those Abused by Priests. "I think that many, many victims still have not disclosed, so the bishops don't know the whole story, and they likely aren't telling all that they do know. They have no incentive to after spending decades and millions keeping it secret."

Susan Archibald, president of the Linkup, another advocacy organization for victims, called for greater attention to those who suffered abuse, rather than perpetrators.

"Now it's time for the next step," she said. "Take appropriate action. Reach out to the victims with positive, real steps. Heal them, treat them, and compensate them with the same level of care that you give the casualties of war, terror, and disaster."

The lay organization Voice of the Faithful said it would not comment on the details of the report until the report is officially released. But executive director Steve Krueger said his organization is concerned that the report will not include data on "the number of bishops who knowingly reassigned priests that had credible allegations of clergy sexual abuse in their records."

"The scope of this, over a 50-year period, really draws our attention to a tragedy of enormous proportions and a tragedy that is due to a failure of leadership, both pastorally as well as from a management perspective," he said.

The draft report said bishops reported more than 11,000 abuse accusations against priests, of which 6,700 were substantiated, 1,000 were unsubstantiated, and the remainder were not investigated because the alleged perpetrators had died, according to CNN. Over half of the accused priests had only one accusation lodged against them, while 3 percent had 10 or more allegations, according to CNN. The cable network also reported that 78 percent of the alleged victims were between the ages of 11 to 17, while nearly 6 percent were 7 or younger.

The study will report only national statistics, not a breakdown by diocese. Boston Archdiocese officials say they plan to release local statistics, as many other dioceses have done, before Feb. 27. A report by Attorney General Thomas F. Reilly of Massachusetts released last July found that 250 priests and other archdiocesan workers were accused of abusing 789 minors since 1940, a period slightly longer than that being examined by the John Jay researchers.

Michael Paulson can be reached at mpaulson@globe.com.

For complete coverage of the priest abuse scandal, go to http://www.boston.com/globe/abuse